U.S. patent application number 10/066131 was filed with the patent office on 2003-07-31 for method and apparatus for substrate processing.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Law, Kam S., White, John M..
Application Number | 20030141820 10/066131 |
Document ID | / |
Family ID | 27610434 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030141820 |
Kind Code |
A1 |
White, John M. ; et
al. |
July 31, 2003 |
Method and apparatus for substrate processing
Abstract
Embodiments of the invention provide methods and apparatus to
process substrates such as flat panel displays, solar panels, etc.
In one aspect, the apparatus provides external toroidal plasma
generation to perform substrate processes such as deposition and
etching of rectangular-shaped substrates. In another aspect, the
apparatus provides external toroidal plasma generation to perform
chamber cleaning by flowing plasma of a process gas such as argon
through a toroidal plasma current path that includes a processing
region to be cleaned, introducing a cleaning gas such as fluorine
into the processing region from a showerhead apparatus, and
cleaning the processing region. In still another aspect, a toroidal
plasma loop is shaped by a plasma shaping apparatus to direct the
plasma across a processing region within the apparatus to improve
process uniformity.
Inventors: |
White, John M.; (Hayward,
CA) ; Law, Kam S.; (Union City, CA) |
Correspondence
Address: |
APPLIED MATERIALS, INC.
2881 SCOTT BLVD. M/S 2061
SANTA CLARA
CA
95050
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
27610434 |
Appl. No.: |
10/066131 |
Filed: |
January 30, 2002 |
Current U.S.
Class: |
315/111.21 ;
315/111.81 |
Current CPC
Class: |
H01J 37/32623 20130101;
H01J 37/3266 20130101; H01J 37/32082 20130101; H01J 37/3244
20130101 |
Class at
Publication: |
315/111.21 ;
315/111.81 |
International
Class: |
H01J 007/24 |
Claims
1. An apparatus for substrate processing, comprising: a chamber
comprising a bottom, a top, and a body disposed between the bottom
and the top; a first plasma source disposed about the chamber and
defining a first plasma current path therein; and at least one
plasma shaping apparatus disposed adjacent the first plasma current
path.
2. The apparatus of claim 1, wherein the first plasma source
comprises a hollow member and wherein the at least one plasma
shaping apparatus is disposed at one end of the hollow member.
3. The apparatus of claim 1, wherein the first plasma source
comprises a pair of outlets wherein each outlet is registered with
respective openings formed in opposing sides of the body.
4. The apparatus of claim 3, further comprising a substrate support
member having a substrate receiving surface and wherein the
respective openings in the opposing sides of the body are at least
as wide as the substrate receiving surface.
5. The apparatus of claim 4, further comprising a showerhead
connected to the top and in facing relationship with the substrate
receiving surface and wherein the respective openings in the
opposing sides of the body are disposed between the showerhead and
the substrate receiving surface.
6. The apparatus of claim 1, further comprising a second plasma
source disposed about the chamber and overlapping at least a
portion of the first plasma source, wherein the second plasma
source defines a second plasma path therein.
7. The apparatus of claim 6, wherein the first and second plasma
sources each define an outlet at each of their respective ends and
wherein the outlets of the first plasma source are registered with
respective openings formed in a first pair of opposing sides of the
body and the outlets of the second plasma source are registered
with respective openings formed in a second pair of opposing sides
of the body.
8. The apparatus of claim 6, wherein the first and second plasma
sources each comprise: a hollow member, wherein each hollow member
defines at least a portion of the respective first and second
plasma paths therein.
9. The apparatus of claim 8, further comprising a coil disposed
proximate each of the hollow members and adapted to produce a
magnetic field therein.
10. The apparatus of claim 8, further comprising at least one other
plasma shaping apparatus disposed adjacent the second plasma
current path.
11. The apparatus of claim 10, wherein each of the plasma shaping
apparatuses are disposed at an outlet of the respective hollow
member.
12. The apparatus of claim 1, wherein the first plasma source
comprises: a hollow member defining at least a portion of the first
plasma current path therein; a plenum coupled to each end of the
member, wherein each plenum is registered with a respective opening
formed in the body.
13. The apparatus of claim 12, wherein the hollow member linearly
traverses the top at about a midsection thereof.
14. The apparatus of claim 12, wherein the hollow member comprises
at least a short transverse section of insulating member adapted to
prevent the formation of a closed electrical path on the hollow
member in about a longitudinal direction.
15. The apparatus of claim 12, further comprising a first antenna
disposed over the top and adapted to inductively couple energy into
the first plasma current path defined within at least a portion of
the hollow member.
16. The apparatus of claim 15, wherein the antenna is a coil wound
about at least one axis generally orthogonal to the first plasma
current path.
17. The apparatus of claim 12, wherein the at least one plasma
shaping apparatus is replaceable with one or more plasma shaping
apparatus each defining a different geometric plasma shaping
opening.
18. The apparatus of claim 1, wherein the at least one plasma
shaping apparatus defines a plasma shape opening registered with an
outlet of the first plasma source and wherein the plasma shape
opening defines at least a first portion and a second portion,
wherein the cross-sectional area of the first portion is different
than the cross sectional area of the second portion.
19. The apparatus of claim 18, wherein the plasma shaping apparatus
comprises a length and width dimension that is greater than the
depth dimension.
20. The apparatus of claim 18, wherein the opening is sized about
the same width and height as the outlet of the first plasma source
and wherein the plasma shape opening define at least two outer
portions and at least one inner portion, wherein the at least two
outer portions are smaller than the at least one inner portion.
21. The apparatus of claim 1, wherein the at least one plasma
shaping apparatus is a magnetic plasma shaping apparatus that
provides a magnetic plasma shape opening within the first plasma
path.
22. The apparatus of claim 21, wherein the magnetic plasma shaping
apparatus comprises at least one magnetic element.
23. The apparatus of claim 20, wherein the at least one magnetic
element comprises at least one of magnets, permanent magnets,
electromagnets, and combinations thereof.
24. The apparatus of claim 21, wherein the magnetic plasma shaping
apparatus position is adjustable relative the plasma.
25. The apparatus of claim 21, wherein the position of the magnetic
element is adjustable relative the plasma.
26. A plasma generating system, comprising: a first hollow member
defining a first plasma current path; a second hollow member
defining a second plasma current path and disposed about orthogonal
with respect to the first hollow member; a first RF source disposed
along a least a portion of the first hollow member and adapted to
produce a first magnetic field within the first hollow member; a
second RF source disposed along a least a portion of the second
hollow member and adapted to produce a second magnetic field within
the second hollow member; a first plasma shaping apparatus disposed
at one end of the first hollow member; and a second plasma shaping
apparatus disposed at one end of the second hollow member.
27. The system of claim 25, wherein the first and second hollow
members are made from a material selected from the group consisting
of aluminum, anodized aluminum, stainless steel, ceramic, glass,
and combinations thereof.
28. The system of claim 25, wherein the first and second hollow
members each have a gas inlet.
29. The system of claim 25, wherein the first pair of plasma
shaping apparatus define a first axis and the second pair of plasma
shaping apparatus define a second axis substantially orthogonal
with respect to the first axis.
30. The system of claim 25, wherein each of the first pair of
plasma shaping apparatus are in facing relationship and each of the
second pair of plasma shaping apparatus are in facing
relationship.
31. The system of claim 25, wherein the first and second pairs of
plasma shaping apparatuses define an opening having a width at
least equal to a substrate to be processed within a region between
the openings defined by the plasma shaping apparatus.
32. The system of claim 25, further comprising: a substrate support
member and a bias RF source coupled to the substrate support
member.
33. The system of claim 31, further comprising: a showerhead and a
showerhead RF source coupled to the showerhead.
34. The system of claim 25, wherein the first and second pair of
plasma shaping apparatuses each define a plasma shape opening
defining a desired plasma density profile therethrough.
35. The system of claim 33, wherein each plasma shape opening
defines at least two plasma shaping regions having different
geometries from one another.
36. A plasma shaping apparatus, comprising: a body including an
inner surface defining an opening to allow plasma therethrough,
wherein the opening has a cross section of varying dimensions to
affect plasma current flowing through the opening.
37. The apparatus of claim 35, further comprising an outer vacuum
chamber mating surface adapted to mate with a vacuum chamber
surface, and a plasma source coupling face adapted to be coupled to
a plasma source.
38. The apparatus of claim 35, further comprising an inner face
adapted to communicate with a processing region of a vacuum chamber
defining the vacuum chamber surface.
39. The apparatus of claim 35, wherein the body is replaceable with
one or more other plasma shaping apparatuses each having an opening
with a different cross-sectional geometry.
40. The apparatus of claim 35, comprising movable portions which
allow the shape of the opening to be changed during a process or
between sequential processes to produce a desired plasma
distribution in the process region.
41. The apparatus of claim 35, comprising at least one magnetic
element defining the inner surface to provide at least one magnetic
field to form the opening therein.
42. The apparatus of claim 40, wherein the at least one magnetic
element comprises electromagnets, permanent magnets, and
combinations thereof.
43. The apparatus of claim 40, wherein the opening is defined by at
least one magnetic field wherein the at least one magnetic field is
adjusted to define the magnetic opening generally orthogonal to and
within the plasma current flow.
44. The apparatus of claim 40, wherein the at least one magnetic
element is defined by a first magnetic element disposed adjacent to
and juxtaposed a second magnetic element, wherein the magnetic
fields generated by the first and second magnetic elements define
the at least one magnetic opening.
45. A method of substrate processing, comprising: flowing a first
gas into a first plasma current path defined by a first hollow
member located external to a processing region; applying power to a
first antenna adjacent the first hollow member to inductively
couple energy into the first gas to form a first plasma current
generating a first plasma from the first gas; flowing the first
plasma generating current across the processing region and through
another end of the first hollow member to define a first closed
plasma current path; and flowing a process gas through a showerhead
into the processing region and forming a plasma of the process gas
adjacent a substrate using the first plasma of the first gas.
46. The method of claim 44, wherein the first gas comprises at
least one of nitrogen, hydrogen, oxygen, nitrous oxide, any of the
Group VIII noble gases including argon and helium, ammonia,
chlorine, boron trichloride, hydrogen chloride, and combinations
thereof.
47. The method of claim 44, wherein the process gas comprises at
least one of a deposition gas, cleaning gas, etch gas, and
combinations thereof.
48. The method of claim 44, wherein the process gas comprises
Trimethylsilane, silane, disilane, chlorinated silanes, TEOS,
H.sub.2, NF.sub.3, Ar, He, and combinations thereof.
49. The method of claim 44, further comprising shaping the plasma
current with a first and second plasma shaping apparatus located
adjacent each end of the first hollow member.
50. The method of claim 48, wherein flowing the first gas adjacent
each of the respective plasma shaping apparatuses comprises flowing
the gases through an opening defined by each of the respective
plasma shaping apparatuses, wherein each opening defines
geometrically differently shaped regions.
51. The method of claim 49, comprising adjusting the geometry of
the plasma-shaping apparatuses.
52. The method of claim 49, comprising exchanging one or more of
the plasma-shaping apparatuses with one or more plasma shaping
apparatuses having different geometrically shaped regions.
53. The method of claim 49, wherein the opening is registered with
an outlet of the external plasma source and wherein the plasma
shape opening defines a first portion and a second portion, wherein
the second portion is narrower than the first portion.
54. The method of claim 48, further comprising flowing a second gas
in a second plasma current path defined by a second hollow member
located external to the processing region.
55. The method of claim 53, further comprising applying RF power to
a second antenna in order to inductively couple energy into the
second plasma current path and generating a second plasma from the
second gas.
56. The method of claim 54, wherein the first and second gas
comprise at least one of nitrogen, hydrogen, oxygen, nitrous oxide,
any of the Group VIII noble gases including argon and helium,
ammonia, chlorine, boron trichloride, hydrogen chloride, and
combinations thereof.
57. The method of claim 54, wherein the first gas and the second
gas are the same.
58. The method of claim 54, wherein the process gas comprises at
least one of a deposition gas, etch gas, cleaning gas, or
combinations thereof.
59. The method of claim 54, wherein the process gas comprises
Trimethylsilane, SiH.sub.4, disilane, chlorinated silanes, TEOS,
H.sub.2, NF.sub.3, Ar, He, and combinations thereof.
60. The method of claim 54, further comprising flowing the second
plasma current adjacent a third plasma shaping apparatus adjacent
one end of the second hollow member, and flowing a second plasma
current across the processing region and adjacent a fourth plasma
shaping apparatus located adjacent another end of the second hollow
member to define a second closed plasma current path.
61. The method of claim 58, wherein flowing the first gas and
second gas adjacent each of the respective plasma shaping
apparatuses comprises flowing the gases through an opening defined
by each of the respective plasma shaping apparatuses, wherein each
opening defines geometrically differently shaped regions.
62. The method of claim 59, comprising adjusting the geometry of
the plasma-shaping apparatuses.
63. The method of claim 59, comprising exchanging one or more of
the plasma-shaping apparatuses with one or more plasma shaping
apparatuses having different geometrically shaped regions.
64. The method of claim 59, wherein the opening is registered with
an outlet of the external plasma source and wherein the plasma
shape opening defines a first portion and a second portion, wherein
the second portion is narrower than the first portion.
65. The method of claim 48, wherein the plasma shaping apparatus is
a magnetic plasma shaping apparatus.
66. The method of claim 63, wherein the plasma-shaping apparatus
comprises at least one magnetic field within the opening to shape
the plasma within the first plasma current path.
67. The method of claim 64, comprising changing the magnetic field
during a process or between sequential processes to shape the
plasma.
68. The method of claim 65, wherein the plasma shaping apparatus
includes at least one magnetic element and wherein changing the
magnetic field comprises adjusting the at least one magnetic
element.
69. The method of claim 66, wherein adjusting the magnetic element
c6 mprises positioning the magnetic element closer to or further
from the plasma.
70. The method of claim 66, wherein the magnetic element is an
electromagnet coupled to a current source to induce a magnetic
field and wherein adjusting the magnetic element comprises
adjusting the current source to increase or decrease the magnetic
field.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method and apparatus for
substrate processing. More specifically, the invention relates to a
method and apparatus for performing processing steps such as
deposition and/or etching of a substrate and/or process chamber
cleaning.
[0003] 2. Background of the Related Art
[0004] In the fabrication of integrated flat panel displays (FPD)
and solar cells, electrically functional devices are formed by
depositing and removing multiple layers of conducting,
semiconducting, and dielectric materials from a substrate.
Processing techniques used to create FPDs and solar cells can
include chemical vapor deposition (CVD), plasma-enhanced chemical
vapor deposition (PECVD), physical vapor deposition (PVD), etching,
and the like.
[0005] Plasma processing is particularly well suited for the
production of integrated flat panels because of the relatively
lower processing temperatures required to deposit films having good
film quality. Generally, plasma-processing applications can be
characterized by the kinetic energy of the ions in plasma, and by
the level of direct exposure of the substrate or film being
processed to the plasma. For example, applications sensitive to
substrate or film damage generally require low-kinetic energy ions
from the plasma, while applications such as anisotropic etching of
silicon dioxide require ions with higher kinetic energy.
[0006] The basic methods for plasma processing include DC
discharge, RF discharge, and microwave discharge. One example of a
plasma-processing chamber places the substrate on a substrate
support having an electrode opposite a planar electrode. The planar
electrode is used to couple high frequency power to the electrode
to form a plasma between the electrode and the planar electrode.
However, some devices or materials are not compatible with this
type of plasma formation particularly because the plasma includes
high-energy photons that cause undesirable substrate heating. To
overcome this issue, another approach to plasma processing
generates plasma in a remote location i.e., in a remote plasma
source, (RPS) and couples the plasma to the processing chamber.
Various types of remote plasma generators have been developed
including magnetron sources coupled to a cavity, microwave
irradiation directed at the plasma precursor, and others.
Unfortunately, a portion of the energy within the plasma is lost to
the conduits used to transport the plasma from the remote location
which may affect the substrate processing efficiency.
[0007] Conventional inductively coupled RF plasma sources are often
used because they can generate large-area plasmas and generally
have a higher processing rate than capacitively coupled sources and
most remote plasma sources. In principle, inductively coupled
plasma systems permit generation of high-density plasma in one
portion of the processing chamber (e.g., above the substrate being
processed) and sufficiently far away that the substrate is not
directly exposed to the plasma.
[0008] External toroidal plasma systems have been developed to
further shield the substrate from plasma generation, provide a more
uniform plasma across the substrate surface, and to overcome the
disadvantages of the conventional inductively coupled plasma
sources. One such system is described in U.S. patent application
Ser. No. 09/638,075 entitled "Externally Excited Toroidal Plasma
Source" filed Aug. 11, 2000. In this case, plasma is created within
one or more conduits that extend externally from and are coupled to
a processing region within a processing chamber. The conduits and
processing region define a closed plasma loop (e.g., toroidal)
path. The plasma and plasma currents are bound within the path by
plasma sheaths formed at the various conductive surfaces that
include the substrate and the adjacent walls of the processing
region and the inner conduit surfaces.
[0009] Conventional toroidal plasma processing systems used for
processes such as etching have proven effective on smaller size
round substrates up to about 300 mm. Generally, the plasma current
flow through the toroidal processing region is constrained between
an upper chamber surface sheath and the substrate to cover more
substrate surface area, thereby minimizing the amount of plasma
needed and maximizing the plasma energy used. However, the
efficient use of toroidal plasma processing systems to process
substrates is detrimentally affected by the increasing size of
substrates. The problems associated with toroidal plasma processing
systems are particularly dramatic on rectangular shaped substrates
having surface areas approaching a square meter, such as FPDs,
solar panels, and the like. As substrates increase in size, the
plasma current path distance and surface area coverage increases
resulting in an increase in plasma current resistance. In addition,
the increasing size of substrates adversely affects plasma density
uniformity. As the substrate size is increased, plasma density
uniformity becomes increasingly difficult to maintain causing
processing problems such as non-uniform deposition and etching. For
example, deposition may be unacceptably thick or thin on the edges
and near the corners effectively reducing the usable substrate
surface area.
[0010] Over time, process cycles (e.g., deposition and etching)
leave a residue on chamber components. In some cases, this residue
can interfere with the process being performed in the chamber and
result in defective substrates. Accordingly, process chambers
require periodic cleaning to ensure proper operation. One common
way to accomplish this is to use a plasma-excited gas mixture that
reacts with the residue, turning it into a volatile compound that
can then be flushed from the system in preparation for the next
substrate process. Often, a cleaning plasma is provided by biasing
a pair of electrodes (typically, a showerhead and a substrate
support member) to capacitively couple energy into a processing
region of the processing chamber. Unfortunately, under direct
exposure to the plasma, the showerhead and substrate support member
can become damaged by the ions of the plasma. Damage to the chamber
components often reduces subsequent processing effectiveness and
requires additional processing chamber maintenance, thereby
increasing production cost.
[0011] Because of this issue, it has recently become more common to
remotely-excite the cleaning gas in a volume that is physically
removed from the processing electrodes. However, this practice
comes with its own limitations as the excited reactants are
remotely generated they must therefore be transported some distance
to the processing volume to be effective in cleaning the residue
from the processing system. This transport distance can be
minimized as much as possible but still some of the reactants will
become de-activated due to the inevitable wall interactions they
unavoidably undergo along the way. Therefore, there is a need for
method and apparatus to provide uniform plasma processing,
including efficient cleaning, within a substrate processing system
adapted to process large area substrates.
SUMMARY OF THE INVENTION
[0012] Aspects of the invention generally provide an apparatus and
method to perform plasma processing such as deposition, etching,
and chamber cleaning. In one embodiment, a chamber comprises a
body, a bottom, a lid, and a substrate support member disposed
within the chamber. The lid, substrate support, and body define a
processing region coupled to a pump adapted to maintain gas
pressure therein. The chamber further comprises a RF source
provided to excite plasma therein. An external structure defines a
first toroidal plasma current path extending through the processing
region and at least one plasma shaping apparatus is disposed within
the first toroidal plasma current path to direct plasma
distribution within the processing region.
[0013] In another embodiment, the invention provides a plasma
generating system, comprising a first hollow member defining a
first plasma current path and a second hollow member defining a
second plasma current path disposed substantially crosswise with
respect to the first hollow member. A first electromagnetic source
is disposed along a least a portion of the first hollow member and
adapted to produce a first magnetic field within the first hollow
member. A second electromagnetic source is disposed along a least a
portion of the second hollow member and adapted to produce a second
magnetic field within the second hollow member. The plasma
generating system also includes a first plasma shaping apparatus
disposed on at least one end of the first hollow member, and a
second plasma shaping apparatus disposed on at least one end of the
second hollow member.
[0014] In another embodiment, the invention provides a plasma
shaping apparatus, comprising a body, including an inner surface
defining a symmetrical opening to allow plasma current flow
therethrough where the opening has a cross section of varying
dimensions to affect the density distribution of plasma current
flowing through the opening.
[0015] In another embodiment, the invention provides a method of
substrate processing, comprising flowing a first gas into a first
plasma current path defined by a first hollow member located
external to a processing region, applying power to a first antenna
adjacent the hollow member in order to inductively couple energy
into the first plasma current path to provide a first plasma
current and to generate a first plasma from the first gas. The
method further includes flowing the first plasma current through a
processing region adjacent a substrate and through another end of
the first hollow member to define a first closed plasma current
path. The method further includes flowing a process gas through a
showerhead into the processing region and generating a plasma of
the process gas adjacent the substrate using the plasma of the
first gas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] So that the manner in which the above recited features,
advantages and aspects of the invention are attained and can be
understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
[0017] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0018] FIG. 1 is a plan-view of a large-area plasma-processing
tool.
[0019] FIG. 2 is a top perspective view of a processing chamber of
the large-area plasma-processing tool of FIG. 1.
[0020] FIG. 3 is a top view illustrating a processing chamber of
the large-area plasma-processing tool of FIG. 1.
[0021] FIG. 4 is side view of illustrating a processing chamber of
the large-area plasma-processing tool of FIG. 1.
[0022] FIG. 5 is a cutaway side view illustrating a processing
chamber of the large-area plasma-processing tool of FIG. 1.
[0023] FIGS. 6A and 6B are top and side views respectively
illustrating one type of coil antenna arrangement.
[0024] FIGS. 7A and 7B are top and side views respectively
illustrating one type of coil antenna arrangement.
[0025] FIG. 8 is a side view of a plasma shaping apparatus.
[0026] FIG. 9 is a side view of a plasma shaping apparatus.
[0027] FIG. 10 is a side view of a plasma shaping apparatus.
[0028] FIG. 11 is a top view of a processing chamber of the
large-area plasma-processing tool of FIG. 1 including four magnetic
plasma shaping apparatuses.
[0029] FIGS. 12A and 12B are top and side views illustrating one
embodiment of an electromagnetic plasma shaping apparatus of FIG.
11.
[0030] FIGS. 13A and 13B are top and side views illustrating one
embodiment of an electromagnetic plasma shaping apparatus of FIG.
11.
[0031] FIGS. 14A and 14B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0032] FIGS. 15A and 15B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0033] FIGS. 16A and 16B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0034] FIGS. 17A and 17B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0035] FIGS. 18A and 18B are a top and side view illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0036] FIGS. 19A and 19B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0037] FIGS. 20A and 20B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
[0038] FIGS. 21A and 21B are top and side views illustrating one
embodiment of a magnetic plasma shaping apparatus of FIG. 11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] Aspects of the invention have particular advantages in a
multi-chamber processing system, also known as a cluster tool,
which is commonly used in the semiconductor industry. Additionally,
aspects of the invention are and well suited for supporting the
toroidal substrate plasma-processing chamber described herein. A
cluster tool is a modular system comprising multiple chambers that
perform various functions including substrate heating,
center-finding and orientation, annealing, deposition, etching, and
the like. The multiple chambers are mounted to a central transfer
chamber which houses a robot adapted to shuttle substrates between
the chambers. The transfer chamber is typically maintained at a
vacuum condition and provides an intermediate stage for shuttling
substrates from one chamber to another and/or to a load lock
chamber positioned at a front end of the cluster tool.
[0040] FIG. 1 is a plan view of a processing system 100 for
semiconductor processing. The processing system 100 generally
comprises a plurality of chambers and robots and is preferably
equipped with a process system controller 102 programmed to carry
out the various processing methods performed in the processing
system 100. A front-end environment 104 is shown positioned in
selective communication with a pair of load lock chambers 106. Pod
loaders 108A-B disposed in the front-end environment 104 are
capable of linear, rotational, and vertical movement to shuttle
substrates between the load locks 106 and a plurality of substrate
cassettes 105 which are mounted on the front-end environment
104.
[0041] The load locks 106 provide a first vacuum interface between
the front-end environment 104 and a transfer chamber 110. Two load
locks 106 are provided to increase throughput by alternatively
communicating with the transfer chamber 110 and the front-end
environment 104. Thus, while one load lock 106 communicates with
the transfer chamber 110, a second load lock 106 may communicate
with the front-end environment 104. A robot 113 is centrally
disposed in the transfer chamber 110 to transfer substrates from
the load locks 106 to one of the various processing chambers 114 or
holding chambers 116. The processing chambers 114 are adapted to
perform any number of processes such as film deposition, annealing,
etching, while the holding chambers 116 are adapted for processes
such as orientation and cool down.
[0042] FIGS. 2, 3, and 4 are a top perspective view, top view, and
side view, respectively, illustrating one embodiment of a
processing chamber 114. In general, the processing chamber 114 has
a polygonal shape in order to accommodate polygonal shaped
substrates. The processing chamber 114 includes a body 116 having
an opening 156 formed therein and shaped to accommodate the
transfer of substrates into and out the processing chamber 114 by
operation of the robot 113 (shown in FIG. 1). The opening 156 is
selectively sealed by a sealing mechanism such as a gate valve or
slit valve apparatus (not shown). Illustratively, only one opening
156 is shown. However, in other embodiments, two or more openings
may be provided to allow access to the chamber through other
chamber walls.
[0043] The processing chamber 114 further includes a first external
hollow conduit 124 and a second external conduit 125 adapted to
hold a process and/or cleaning gas therein. The gases are provided
to the first and second hollow conduits 124, 125 via conduit gas
inlets 111, 123, respectively. The conduits 124, 125 may be coupled
to one or more external gas sources (not shown) containing gases
such as argon, helium, hydrogen, oxygen, NF.sub.3, and like. The
conduits 124, 125 may be formed of a relatively thin conductor such
as, aluminum, anodized aluminum, stainless steel, polymers,
ceramics, and the like, sufficiently strong to withstand a vacuum
therein.
[0044] The first external hollow conduit 124 and second external
hollow conduit 125 are disposed over and traverse a lid 118 of the
processing chamber 114. The conduits 124, 125 are aligned generally
orthogonal and are disposed above one another where the first
conduit 124 is taller with respect to the lid 118 to allow the
second conduit 125 to pass between the lid 118 and the first
conduit 124. In one aspect, the conduits 124,125 are coupled to the
body 116 using fasteners such as screws, bolts, and the like. The
first and second conduits 124, 125 are coupled to an internal
processing cavity of the processing chamber 114 discussed below
with reference to FIG. 5. Although shown extending externally
outward from the processing chamber 114 as separate components, the
first and second conduits 124, 125 may be formed integrally to the
lid 118.
[0045] First and second coil antennas 137, 138 are disposed
proximate the conduits 124, 125, respectively and are adapted to
couple RF energy into a process gas and/or cleaning gas within each
respective conduit 124, 125. The RF energy excites the gas within
each respective conduit 124, 125 to form plasma therein. The
details and operation of the conduits 124, 125, the coil antennas
137, 138, and the processing chamber 114 will be discussed below
with respect to FIG. 5. While the coil antennas 137, 138 may be
used to couple RF energy into the conduits 124, 125, it is
contemplated that the RF energy can also be coupled into the plasma
within the conduits 124,125 using magnetic-flux-concentrating
materials such as ferrites.
[0046] FIG. 5 is a cross-section of one embodiment of a processing
chamber 114. FIGS. 1-4 may be referenced as needed with the
discussion of FIG. 5. The processing chamber 114 includes a
processing chamber body 116 and lid 118. The processing chamber
body 116 and lid 118 define a cavity within the processing chamber
114 that includes a processing region 120 therein. A showerhead 122
disposed within the lid 118 defines the upper boundary of the
processing region 120. The showerhead 122 comprises a gas inlet 117
and a plurality of dispersion holes 121 to allow delivery of one or
more processing gases such as SiH.sub.4, N.sub.2O, NH.sub.3,
CH.sub.4, TEOS, O.sub.2, H.sub.2, He, WF.sub.6, NF.sub.3, CF,
C.sub.XH.sub.YF.sub.Z, C.sub.xF.sub.y, Trimethylsilane (TMS),
therethrough into the processing region 120. In one aspect, the
showerhead 122 acts as an anode coupled to a showerhead RF source
119 and matching network 128 to capacitvely couple RF energy to the
processing region 120.
[0047] The processing chamber 114 also includes a movable substrate
support member 130, also referred to as a susceptor, which can be
raised or lowered in the processing chamber 114 by a lifting
apparatus 133. A substrate support surface 131 of the substrate
support member 130 defines the lower boundary of the processing
region 120. The substrate support member 130 may be heated using
resistive heaters, lamps, or other heating devices commonly used in
the field of electronic device fabrication. A shaft 132 of the
substrate support member 130 is moveably disposed through a floor
of the body 116. In one aspect, an insulating o-ring 144 located in
the floor and disposed around the shaft 132 can be used to
electrically isolate the support member 130 while also providing a
vacuum seal. In one aspect, a bellows 156 is coupled to an upper
sealing ring 157A, disposed on the body 116, and is also coupled to
lower sealing ring 157B disposed about the shaft 132 to provide an
alternative vacuum seal. The substrate support 130 can then be
coupled to a bias RF source 146 through a matching network 147. In
operation, the bias RF source 146 is adjusted to vary the
attraction of ion species toward the substrate.
[0048] In one aspect, the lid 118 includes an exhaust port 142
defined by a peripherally-mounted plenum structure 143 attached to
and circumventing the perimeter of the lid 118 to allow process
gases to be evacuated from the processing region 120. An insulating
ring 155 electrically insulates the peripherally-mounted plenum
structure 143 and lid 118 from the showerhead 122. A vacuum pump
139 is coupled to the processing chamber 114 to control the chamber
pressure therein. The vacuum pump 139 may be any pump adapted to
achieve and maintain a desired pressure. Illustrative pumps that
may be used to advantage include turbopumps, cryo pumps, roughing
pumps, and any combination thereof. Illustratively, the vacuum pump
139 communicates with the processing chamber 114 via an exhaust
coupling 140. Specifically, the exhaust coupling 140 is connected
at one end to the vacuum pump 139 and at another end to the plenum
structure 143. While, a pumping position is shown where the gases
are evacuated from the lid 118 forming a top-pumping configuration,
it is contemplated that the vacuum pump could be coupled to the
cavity from any location. For example, the vacuum pump 139 may be
coupled to the bottom of the body 116 through a bottom exhaust port
(not shown) forming a bottom-pumping configuration.
[0049] The first and second external hollow conduits 124,125 are
disposed in alignment with a first opening pair 170A-B and second
opening pair 171A-B formed within the body 116 to couple the
conduits 124, 125 to the processing region 120 therein. The first w
and second opening pairs 170A-B, 171A-B are generally axially
aligned on opposite sides of the substrate support 130 and are
positioned such that during processing they define a plasma current
path extending across the processing region 120 and between the
substrate support member 130 and showerhead 122. Internally, each
conduit 124,125 shares the same evacuated atmosphere as exists
elsewhere in the chamber cavity, including the processing region
120. During operation, the conduits 124,125 provide an external
plasma current flow path from the processing region 120 and are
coupled to the internal plasma current paths extending across the
processing region via the first and second opening pairs 170A-B,
171A-B respectively. Thus, the conduits 124, 125 and the internal
processing region 120 define two separate toroidal plasma current
paths providing plasma current ingress into and egress from the
processing chamber 114. Illustratively, the first conduit 124 and
processing region 120 define a first toroidal plasma current path
160. The second conduit 125 and processing region 120 define a
second toroidal plasma current path 161. Notwithstanding the use of
the term "toroidal", the trajectory of the closed path through each
conduit 124, 125 and the processing region 120 may be circular,
non-circular, square, rectangular, or any other shape either
regular or irregular. Illustratively, the conduits 124, 125 and the
toroidal plasma current paths 160-161 are generally rectangular in
cross section but may be any other cross-sectional shape such as
polygon, circular, elliptical and the like.
[0050] In one aspect, to ensure substantially equal plasma density,
it is desirable to keep the plasma current paths 160-161 about the
same length by adjusting the conduits 124,125 lengths. As the
substrates and therefore the processing chamber 114 are often
rectangular in shape, the narrower width of the processing chamber
114 relative to its length makes it desirable to position the first
hollow conduit 124, which spans the width, above the second hollow
conduit 125.
[0051] In another aspect, the first and second hollow conduits 124,
125 are generally narrower in width than the processing chamber 114
to facilitate inductive coupling of the excitation source energy to
the plasma inside the conduit. Therefore, to mate with the first
and second opening pairs 170A-B and 171A-B the first and second
hollow conduits 124, 125 increase in width from a narrower upper
member 124A, 125A to two wider lower ends 124B-C, 125B-C, that are
adapted to mate with their respective opening pairs 170A-B, 171A-B.
For example, the first hollow conduit 124 is registered with and
coupled on a first lower end 124B-C, to the first inlet pair
170A-B. The second hollow conduit 125 is registered with and
coupled on a second lower end 125B-C, to the second inlet pair
171A-B.
[0052] In one aspect, the first coil antenna 137 includes one or
more turns about a longitudinal axis and is adapted to couple
energy (illustratively RF energy) into the first conduit 124 from a
first inductive RF source 125 through a matching network 126. The
longitudinal axis of the first coil antenna 137 is disposed
generally orthogonal to the longitudinal axis of the first conduit
124. The second coil antenna 138 includes one or more turns about a
longitudinal axis and is adapted to couple energy (illustratively
RF energy) into the second conduit 125 from a second inductive RF
source 129 through an optional matching network 127 for better
power utilization efficiency. The longitudinal axis of the second
coil antenna 138 is disposed generally orthogonal to the
longitudinal axis of the second conduit 125. While each coil
antenna 137, 138 is wound in a generally flat elliptical shape that
extends along a length of a respective conduit 124, 125, it is
contemplated that the coil antennas 137, 138 can be of any shape or
length adapted to couple RF energy into the respective first or
second conduits 124, 125.
[0053] Each coil antenna 137,138 forms a primary transformer turn
and the toroidal plasma current paths 160-161 define a secondary
transformer turn, respectively. For example, the first coil antenna
137 forms a primary transformer turn and the plasma within the
first toroidal path 160 forms a secondary transformer turn. In
order to prevent electrically-conductive hollow conduits 124,125,
from shorting the electric field generated by the magnetic field of
the coil antennas (and thereby eliminating the possibility of
generating a plasma within the conduits) an insulating gap 153
(only one gap is shown) extends across each hollow conduit 124,125.
The gaps 153 are enclosed by a ring 154 of insulating material such
as ceramic, glass, and the like adapted to provide electrical
insulation while maintaining vacuum integrity of the conduits 124,
125. Alternatively, the hollow conduits 124,125 may be formed from
a non-conductive material such as ceramic, glass, and the like, to
eliminate any electric paths altogether without the need for the
gaps 153.
[0054] In one aspect, the first and second coil antennas 137, 138
are wound so the currents within the coil antennas 137, 138 are
about parallel to the plasma current flow within the respective
first and second plasma current paths 160,161. As a result, the
magnetic fields produced by the currents within each antenna coil
137, 138 are generally orthogonal to the direction of current flow
through the first and second plasma current paths,
respectively.
[0055] While the axial alignment of each coil 137, 138 relative to
their respective conduits 124, 125 aligns the currents within the
coil antennas 137, 138 to their respective plasma currents, the
coil antennas 137, 138 may be placed in any position to achieve a
desired plasma energy density. For example, the coil antennas 137,
138 may be wound such that the axis of the coil antennas 137, 138
are generally orthogonal to the longitudinal axis of their
respective conduits 124, 125. Illustratively, FIGS. 6A and 6B
depict one aspect whereby the first coil antenna 137 is wound such
that the axis of the first coil antenna 137 is generally orthogonal
to the longitudinal axis of its respective conduit 124. In another
aspect, a portion of each antenna coil 137, 138 is wound on
opposing sides of their respective conduits 124, 125 to enhance the
energy coupling. For example, FIG. 6B illustrates the first coil
antenna 137 wound on opposing sides of its conduit 124.
[0056] The coil antennas 137, 138, may also be wound in a helical
flat winding, such that the windings are in closer proximity to the
conduits 124, 125, thereby increasing the RF energy coupled into
the plasma. For example, FIGS. 7A and 7B illustrate another
configuration whereby the first coil antenna 137 is wound in a flat
helical shape and whereby the longitudinal axis of the first coil
antenna 137, 138, is aligned generally orthogonal to the
longitudinal axis of their respective conduits 124, 125. The energy
coupling into the plasma may also be increased by positioning the
conduit between the windings so that a portion of the coil antenna
137, 138 are on opposing sides of the conduit 124, 125. For
example, FIG. 7B illustrates the first coil antenna 137 is wound as
a flat helical shape on opposing sides of the first conduit
124.
[0057] Referring back to FIG. 5, in one aspect, to provide a
uniform coverage of the substrate surface, the toroidal plasma
current paths 160,161 are aligned generally orthogonal so that the
plasma from the first plasma current path 160 crosses processing
region 120 generally orthogonal to the second plasma current path
161. The toroidal plasma current paths 160-161 are generally
constrained within their respective conduits 124, 125, however, it
is contemplated that the plasma formed in the shared volume above
the substrate within the processing region 120 will allow "leakage"
of currents between the plasma current paths 160, 161. To some
extent this plasma leakage will aid in achieving a uniform plasma
density in the shared volume above the substrate, however, it must
be controlled to the extent necessary to affect uniform deposition
and etching. In one aspect, to control the amount of plasma leakage
between the first path 160 to the second path 161, a first plasma
shaping apparatus pair 150A-B is disposed within the first opening
pair 170A-B. Each member of the first plasma shaping apparatus pair
150A-B are aligned to generally face the other member across the
processing region 120. In order to control the amount of plasma
leakage from the second path 161 to the first path 160, a second
plasma shaping apparatus pair 151A-B is disposed within the second
opening pair 171A-B. Each member of the second plasma shaping
apparatus pair 150A-B are aligned to generally face the other
member across the processing region 120. The function of the plasma
shaping apparatuses 150A-B, 151A-B is also to ensure that the
natural tendency of the plasma in each toroidal plasma current loop
160,161 to take the shortest possible (minimum resistance) path
across the shared volume does not result in the plasma being
confined to narrow "bands" across mutually-orthogonal median lines
of the volume. For example, if the plasma current density was
greater along the middle of the substrate, the deposition or etch
process would be exaggerated across the substrate middle affecting
the process uniformity.
[0058] The first conduit 124, the first opening pair 170A-B, and
the first plasma shaping apparatus pair 150A-B define a first
external structure 149A representing a portion of the first
toroidal plasma current path 160. The second conduit 125, the
second opening pair 171A-B, and the second plasma shaping apparatus
pair 151A-B define a second external structure 149B representing a
portion of the second toroidal plasma current path 161. While the
first and second plasma shaping apparatus pair 150A-B, 151A-B, are
disposed within the first and second opening pair 170A-B, 171A-B,
respectively, it is contemplated that the first and second plasma
shaping apparatus pair 150A-B, 151A-B may be positioned in any
location along the respective paths 160, 161. For example, the
first and second plasma shaping apparatus pair 150A-B, 151A-B, may
be disposed to the first and second lower ends 124B-C, 125B-C, of
the conduits, 124, 125, or may be a coupling member adapted to
couple the lower ends 124B-C, 125B-C, to the body 116 adjacent the
opening pairs 170A-B, 171A-B.
[0059] Each member of the plasma shaping apparatus pairs 150A-B,
151A-B has an opening, the shape of which in turn determines the
distribution of the plasma within the volumes on either side of the
apparatus pairs 150A-B, 151A-B. The current produced by the induced
electric field, which creates and sustains the plasma in each
toroidal plasma current path 160, 161, is constricted by the
smaller portions of the opening to alter the plasma distribution
within the processing region 120. In one aspect, the plasma shaping
apparatus pairs 150A-B, 151A-B are formed from material about 1/8"
inch to about 1/4" inch thick to provide a plasma constriction
momentarily increasing the plasma current density. In general, the
plasma shaping apparatus pairs 150A-B, 151A-B are formed of
metallic materials such as aluminum, stainless steel, anodized
aluminum.
[0060] In one aspect, the plasma shaping apparatus pairs 150A-B,
151A-B are adapted to be changeable between and/or during a process
to create different plasma current flow patterns across the
processing region 120. For example, FIG. 8 illustrates one
embodiment for one member 150A of the first plasma shaping
apparatus pair 150A-B having a larger center cross sectional area
166A and two outer smaller regions 167A. The inner periphery 163A
acts to define a desired plasma current distribution in the
processing region 120 by creating a distributed impedance to the
current flowing in the plasma. A higher current density at the
center 166A of the opening may be used, for example, to increase
the deposition along the central region of the substrate parallel
to the current flow through the plasma shaping apparatus pair
150A-B.
[0061] FIG. 9 illustrates another embodiment of one member 150A of
the first plasma shaping apparatus pair 150A-B where an inner
periphery 163B defines a narrowed center portion 166B and two
larger outer portions 167B that are generally opposite each other
and on either side of the center portion 166B. As the plasma
current flows through the opening, the constriction at the center
portion 166B forces more of the plasma current through the wider
portions of the opening 167B thereby decreasing plasma density
along the middle of the plasma current flow within the processing
region 120. During substrate processing, decreasing the plasma
density along the middle of the plasma current flow decreases the
deposition or etching rate along the middle of the substrate.
[0062] It is contemplated that the inner periphery 163A-B may be
adapted to establish any opening to shape the plasma current flow
into any desired density distribution. For example, FIG. 10
illustrates that outer portions 167A-B and the center portion
166A-B may define two or more openings 166C that constrict the
plasma current on the edges and the middle of the processing
region. In another example, with regard to cleaning, the plasma
shaping apparatus pairs 150A-B and 151A-B may be removed entirely.
Additionally, the plasma shaping apparatus pairs 150A-B and 151A-B
may be adapted to have a narrower or larger opening to accommodate
smaller, or larger, substrates within the same chamber,
respectively, or to control the amount of overall ion density
distribution within the processing region 120.
[0063] In one embodiment, the plasma current flow may be shaped
magnetically. FIG. 11 is a top view of one the processing chamber
114 including four magnetic plasma shaping apparatuses 180A-D. In
one aspect, each of the four magnetic plasma shaping apparatuses
180A-D is disposed above and below and across the length of one of
the wider lower ends 124B-C, 125B-C adjacent the chamber 114. The
four magnetic plasma shaping apparatuses 180A-D are adapted to
provide a magnetic field within the hollow conduits 124, 125 at the
lower ends 124B-C, 125B-C, respectively, to form a magnetic opening
to shape the plasma current flow therein.
[0064] The magnetic plasma shaping apparatuses 180A-D include a
plurality of magnetic elements 184 such as electromagnets,
permanent magnets, and the like, disposed above and/or below the
first and second lower ends 124B-C, 125B-C. The magnetic elements
are adapted to provide a desired magnetic field profile which in
turn defines a plasma current flow profile within the lower ends
124B-C, 125B-C to control the plasma current flow through each path
160-161 through the processing region 120. For example, by using a
plurality of magnetic elements 184 having different magnetic field
strengths and/or by varying the position of the magnetic elements
184 along the width and/or proximity to the plasma current therein
of the lower ends 124B-C, 125B-C, a plurality of plasma current
flow profiles may be formed. In one aspect, the magnetic elements
184 include one or more electromagnetic coils coupled to a DC power
source, or sources (not shown), to set the level of the
electromagnetic fields therein. It is contemplated that the
strength of the current within each electromagnetic coil may be
adjusted to alter the magnetic field profile to adjust and/or
define a desired plasma current flow profile from process to
process, or during a particular process.
[0065] In one aspect, the magnetic poles of the magnetic elements
184 are set parallel to define a common magnetic field polarization
with respect to the plasma, thereby minimizing plasma leakage to
the walls of the hollow conduits 124, 125. For example, the south
pole of each magnetic element 184 is set orthogonal to and facing
the plasma.
[0066] It is contemplated that the magnetic poles may be set to any
desired position or configuration to attain a desired magnetic
field profile. For example, FIGS. 12A-B through 21A-B are cut away
top and side views illustrating various configurations of a first
magnetic plasma shaping apparatuses 180A using magnetic elements
184 including electromagnetic coils and/or permanent magnets. While
only one magnetic plasma shaping apparatus 180A is shown, the FIGS.
12A-B through 21A-B illustrate only a few of the plurality of
configurations for each of the four magnetic plasma shaping
apparatuses 180A-D.
[0067] FIGS. 12A-B illustrate one embodiment of the first magnetic
plasma shaping apparatus 180A. A plurality of electromagnetic coils
201A-G varying in dimension are disposed above, below, and along
the width of the first lower end 124B and have their longitudinal
axis aligned generally orthogonal to the first plasma current path
160. In one aspect, a plurality of first electromagnetic coils
201A-F are disposed above the first lower end 124B. The first
electromagnetic coils 201A-F have their magnetic poles aligned
with, adjacent, and juxtaposed to a plurality of second
electromagnetic coils 201G disposed below the first lower end 124B.
To form an opposing magnetic field, the magnetic poles of the first
electromagnetic coils 201A-F are generally aligned with and the
same as poles of the second electromagnetic coils 201G. Further,
the magnetic north and south poles of adjacent discrete coils are
adjacent. For example, the magnetic north pole of electromagnetic
coil 201A is facing and adjacent the magnetic south pole of the
electromagnetic coil 201B. Illustratively, the first
electromagnetic coils 201A-F provide an upper magnetic field 188A
adjacent the toroidal path 160. The second electromagnetic coils
201G provide a lower magnetic field 188B adjacent the toroidal path
160 and below the upper magnetic field 188A. The upper and lower
magnetic fields 188A, 188B define a magnetic opening 189A disposed
adjacent the lower end 124B. The magnetic opening 189A is disposed
within and about orthogonal to the plasma current path 160.
[0068] FIGS. 13A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first
electromagnetic coils 202A are disposed above and below and along
the width of the first lower end 124B. The first electromagnetic
coils 202A have their longitudinal axis aligned generally
orthogonal to the first plasma current path 160. In one aspect, the
plurality of first electromagnetic coils 202A are disposed above
the first lower end 124B. The first electromagnetic coils 202A have
their magnetic poles aligned, are adjacent to, and juxtaposed the
plurality of second electromagnetic coils 202G disposed below the
first lower end 124B. To form an opposing magnetic field, the
magnetic poles of the first electromagnetic coils 202A are aligned
with and the same type as the magnetic poles of the second
electromagnetic coils 202G (e.g., south poles are aligned).
Further, the magnetic north and south poles of adjacent discrete
coils are opposite. For example, the magnetic north pole of a first
discrete electromagnetic coil 202A' is facing and adjacent the
magnetic south pole of an adjacent second electromagnetic coil
202A". Illustratively, the first electromagnetic coils 202A provide
an upper magnetic field 188C disposed adjacent the toroidal path
160. The second electromagnetic coils 202H provide a lower magnetic
field 188D disposed adjacent the toroidal path 160 and below the
upper magnetic field 188C. The upper and lower magnetic fields
188C, 188D define a magnetic opening 189B disposed adjacent the
lower end 124B and generally disposed within and orthogonal to the
plasma current path 160.
[0069] FIGS. 14A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first and
second electromagnetic coils 204A-F of varying length are disposed
along the width and above and below the first lower end 124B and
have their longitudinal axis aligned generally aligned with the
first plasma current path 160. In one aspect, the plurality of
first electromagnetic coils 204A-E disposed above the first lower
end 124B. The first electromagnetic coils 204A-E have their
magnetic poles aligned, adjacent to and juxtaposed the plurality of
second electromagnetic coils 204F disposed below the first lower
end 124B. To form an opposing magnetic field, the magnetic poles of
the first electromagnetic coils 204A-E are aligned with the
magnetic poles of the second electromagnetic coils 204F. Further,
the magnetic north and south poles of adjacent discrete coils are
aligned. For example, the magnetic north pole of a first discrete
electromagnetic coil 204A is aligned with the magnetic north pole
of an adjacent second electromagnetic coil 204B. Illustratively,
the first electromagnetic coils 204A-E provide an upper magnetic
field 188E disposed adjacent the toroidal path 160. The second
electromagnetic coils 202F provide a lower magnetic field 188F
disposed adjacent the toroidal path 160 and below the upper
magnetic field 188E. The upper and lower magnetic fields 188E, 188F
define a magnetic opening 189C disposed adjacent the lower end 124B
and generally orthogonal to the plasma current path 160.
[0070] FIGS. 15A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first and
second electromagnetic coils 206A-B are disposed above, below, and
along the width of the first lower end 124B and have their
longitudinal axis aligned generally with the first plasma current
path 160. In one aspect, the plurality of first electromagnetic
coils 206A are disposed above the first lower end 124B. The first
electromagnetic coils 206A have their magnetic poles aligned with
the plurality of second electromagnetic coils 206B disposed below
the first lower end 124B. To form an opposing magnetic field, the
magnetic poles of the first electromagnetic coils 206A are aligned
with the magnetic poles of the second electromagnetic coils 206B
(e.g., south pole of the first coil opposite the south pole of the
second coil). Further, the magnetic north and south poles of
adjacent discrete coils are aligned. For example, the magnetic
north pole of a first discrete electromagnetic coil 206A' is
aligned with the magnetic north pole of an adjacent second
electromagnetic coil 206A". Illustratively, the first
electromagnetic coils 206A provide an upper magnetic field 188G
disposed adjacent the toroidal path 160. The second electromagnetic
coils 206H provide a lower magnetic field 188H disposed adjacent
the toroidal path 160 and below the upper magnetic field 188G. The
upper and lower magnetic fields 188G, 188H define a magnetic
opening 189D disposed adjacent the lower end 124B and generally
orthogonal to the plasma current path 160.
[0071] FIGS. 16A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first and
second electromagnetic coils 208A-F are disposed above, below, and
along the width of the first lower end 124B and have their
longitudinal axis aligned generally orthogonal to the first plasma
current path 160. In one aspect, the plurality of first
electromagnetic coils 208A-E are disposed above the first lower end
124B and have their magnetic poles aligned adjacent to and
juxtaposed the plurality of second electromagnetic coils 208F
disposed below the first lower end 124B. To form an opposing
magnetic field, the magnetic poles of the first electromagnetic
coils 208A-E are aligned with the magnetic poles of the second
electromagnetic coils 208F. Further, the magnetic north and south
poles of adjacent discrete coils are aligned. For example, the
magnetic north pole of a first discrete electromagnetic coil 208A
is aligned with the magnetic north pole of an adjacent second
electromagnetic coil 208B. Illustratively, the upper
electromagnetic coils 208A-E provide an upper magnetic field 1881
disposed adjacent the toroidal path 160. The second electromagnetic
coils 208F provide a lower magnetic field 188J disposed adjacent
the toroidal path 160 and below the upper magnetic field 1881. The
upper and lower magnetic fields 188I, 188J define a magnetic
opening 189E disposed adjacent the lower end 124B and generally
orthogonal to the plasma current path 160.
[0072] FIGS. 17A-B illustrates another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first and
second electromagnetic coils 210A-D are disposed along the width of
the first lower end 124B and have their longitudinal axis aligned
generally orthogonal to the first plasma current path 160. In one
aspect, the plurality of first electromagnetic coils 210A-B
disposed above the first lower end 124B have their magnetic poles
aligned and are adjacent to and juxtaposed the plurality of second
electromagnetic coils 210C-D disposed below the first lower end
124B. To form an opposing magnetic field, the magnetic poles of the
first electromagnetic coils 210A-B are aligned with the magnetic
poles of the adjacent second electromagnetic coils 210C-D. Further,
the magnetic north and south poles of the adjacent discrete coils
210A-B and 210C-D are opposed. For example, the magnetic north pole
of a first discrete electromagnetic coil 210A' is aligned with the
magnetic south pole of an adjacent second electromagnetic coil
210B'. Still further, the magnetic north and south poles of
adjacent first and second electromagnetic coils 210A-D are
opposing. For example, the magnetic south pole of the first
discrete electromagnetic coil 210A is opposite the south pole of an
adjacent second electromagnetic coil 210C. Illustratively, the
plurality of first electromagnetic coils 210A provides an upper
magnetic field 188K disposed adjacent the toroidal path 160. The
plurality of second electromagnetic coils 210C-D provides a lower
magnetic field 188L disposed adjacent the toroidal path 160 and
below the upper magnetic field 188K. The upper and lower magnetic
fields 188K, 188L define a magnetic opening 189F disposed adjacent
the lower end 124B and generally orthogonal to the plasma current
path 160.
[0073] FIGS. 18A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. In one aspect, a plurality
of first and second electromagnetic coils 212A-B are disposed
above, below, and along the width of the first lower end 124B and
have their longitudinal axis aligned generally orthogonal to the
first plasma current path 160. To form an opposing magnetic field,
the plurality of first electromagnetic coils 212A disposed above
the first lower end 124B have their magnetic poles aligned adjacent
to and juxtaposed the plurality of second electromagnetic coils
212B disposed below the first lower end 124B. For example, the
north pole of the first electromagnetic coils 212A are aligned with
the north poles of the second first electromagnetic coils 212B.
Further, the magnetic north and south poles of adjacent discrete
coils are aligned. For example, the magnetic south pole of a first
discrete electromagnetic coil 212A' is aligned with the magnetic
south pole of an adjacent second electromagnetic coil 212A".
Illustratively, the first electromagnetic coils 212A provide an
upper magnetic field 188P disposed adjacent the toroidal path 160.
The second electromagnetic coils 212B provide a lower magnetic
field 188Q disposed adjacent the toroidal path 160 and below the
upper magnetic field 188P. The upper and lower magnetic fields
188P, 188Q define a magnetic opening 189G disposed adjacent the
lower end 124B and generally orthogonal to the plasma current path
160.
[0074] FIGS. 19A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A first and second
electromagnetic coil 214A-B having windings of varying lengths are
disposed along the width of the first lower end 124B and have their
longitudinal axis aligned generally orthogonal to the first plasma
current path 160. In one aspect, to form an opposing magnetic field
the first electromagnetic coil 214A is disposed above the first
lower end 124B, has its magnetic pole aligned with the second
electromagnetic coil 214B disposed below the first lower end 124B.
The magnetic pole of the first electromagnetic coil 214A is
generally aligned with the magnetic pole of the second
electromagnetic coil 214B. Further, the magnetic poles of the first
and second electromagnetic coils 214A-B that face each other are
the same. For example, the magnetic north pole of the first
electromagnetic coil 214A is opposite the magnetic north pole of
the second electromagnetic coil 214B. Illustratively, the first
electromagnetic coils 214A provide an upper magnetic field 188R
disposed adjacent the toroidal path 160. The second electromagnetic
coils 214B provide a lower magnetic field 188S disposed adjacent
the toroidal path 160 and below the upper magnetic field 188R. The
upper and lower magnetic fields 188R, 188S define a magnetic
opening 189H disposed adjacent the lower end 124B and generally
orthogonal to the plasma current path 160. In another aspect, the
first and second coils may include a plurality of coils of varying
length that are disposed upon each other and having their
longitudinal axis aligned. For example, the first electromagnetic
coil 214A may comprise six windings of varying length, each of
which is a separate coil with the longitudinal axis of each of the
six coils aligned.
[0075] FIGS. 20A-B illustrate another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of upper and
lower permanent magnets 216A-B are disposed above, below, and along
the width of the first lower end 124B and have their longitudinal
axis aligned generally orthogonal to the first plasma current path
160. In one aspect, the plurality of first permanent magnets 216A
disposed above the first lower end 124B have their magnetic poles
aligned and are adjacent to and juxtaposed the plurality of second
permanent magnets 216B disposed below the first lower end 124B. To
form an opposing magnetic field, the magnetic poles of the first
permanent magnets 216A are aligned with the same magnetic poles of
the second permanent magnets 216B. For example, the north poles of
the first permanent magnets 216A are opposite the north poles of
the second permanent magnets 216B. Further, the magnetic north and
south poles of adjacent discrete permanent magnets are aligned but
opposite. For example, the magnetic north pole of a first discrete
permanent magnet 216A' is aligned with the magnetic south pole of
an adjacent second discrete permanent magnet 216A". Illustratively,
the plurality of first permanent magnets 216A provide an upper
magnetic field 188T disposed adjacent the toroidal path 160. The
plurality of second permanent magnets 214B provide a lower magnetic
field 188U disposed adjacent the toroidal path 160 and adjacent the
upper magnetic field 188T. The upper and lower magnetic fields
188T, 188U define a magnetic opening 1891 disposed adjacent the
lower end 124B and generally orthogonal to the plasma current path
160.
[0076] FIGS. 21A-B illustrates another configuration of the first
magnetic plasma shaping apparatus 180A. A plurality of first and
second permanent magnets 218A-E of varying dimensions are disposed
above, below, and along the width of the first lower end 124B and
have their longitudinal axis aligned generally orthogonal to the
first plasma current path 160. In one aspect, the plurality of
first permanent magnets 218A-D disposed above the first lower end
124B have their magnetic poles aligned and are adjacent to and
juxtaposed the plurality of second permanent magnets 218E disposed
below the first lower end 124B. To form an opposing magnetic field,
the magnetic poles of the first permanent magnets 218A-D are
aligned with the same magnetic poles of the second permanent
magnets 218E. For example, the north poles of the first permanent
magnets 218A-D are opposite the north poles of the second permanent
magnets 218E. Further, the magnetic north and south poles of
adjacent discrete permanent magnets are aligned. For example, the
magnetic north pole of a first discrete permanent magnet 218A is
aligned with the magnetic north pole of an adjacent second discrete
permanent magnet 218B. Illustratively, the plurality of first
permanent magnets 218A-D provide an upper magnetic field 188V
disposed adjacent the toroidal path 1-60. The plurality of second
permanent magnets 218B provide a lower magnetic field 188W disposed
adjacent the toroidal path 160 and adjacent the upper magnetic
field 188V. The upper and lower magnetic fields 188V, 188W define a
magnetic opening 189J disposed adjacent the lower end 124B and
generally orthogonal to the plasma current path 160.
[0077] FIGS. 12A-B, through FIGS. 21A-B, illustrate only a few of
the plurality of magnetic element 184 configurations. For example,
in one aspect the magnetic elements 184 may be a combination of
both electromagnets and permanent magnets. In another aspect, the
electromagnetic elements 184 may be formed into a single
interchangeable apparatus. In still another aspect, the distance
the electromagnetic elements 184 relative to the plasma may be
adjusted to increase or decrease the magnetic field strength. In
another aspect, the plurality of permanent magnets may be formed
into a single magnet. While in one aspect the magnetic plasma
shaping apparatuses 180A-D may be used alone, it is contemplated
that one or more of the magnetic plasma shaping apparatuses 180A-D
may be used in combination with the plasma shaping pairs 150A-B,
151A-B to define a desired plasma current profile.
[0078] Operation
[0079] During substrate processing, a gas is introduced into the
hollow conduits 124,125 via gas inlets 111 and 123 respectively.
The respective excitation sources 125 and 126 generate a current
within the coil antennas 137,138, to couple electromagnetic energy
into the gas within each conduit 124, 125, thereby striking plasma
therein. A separate trigger circuit (not shown in illustrations)
may also be used to facilitate plasma ignition. Plasma current and
plasma then circulate though each toroidal plasma current path
160-161 through the respective plasma shaping apparatus pairs
150A-B and 151A-B and/or magnetic plasma shaping apparatuses 180A-D
to control the flow of current and density of plasma within the
processing region 120. The amount of power applied to the coil
antennas 137, 138 also determines the amount of power coupled into
the plasma between the substrate and showerhead 122.
[0080] During a deposition process, typically a
non-silicon-containing gas such as nitrogen, hydrogen, oxygen,
nitrous oxide, ammonia, any of the Group VIII noble gases including
argon and helium, or like is flowed through each toroidal plasma
current path 160-161 through gas inlets 111, 123. Subsequently or
simultaneaously, a silicon-containing gas such as Trimethylsilane
(TMS), silane, TEOS, or the like is flowed from a gas inlet 117
into the showerhead 122 and then through the showerhead gas
dispersion holes 121. Some amount of non-silicon-containing gas may
also be mixed with the silicon-containing gas and flowed through
the showerhead 122. The gas or the gas mixture entering through the
showerhead 122 becomes the process gas and composes the portion of
the toroidal plasma loop 160, 161 that is above a substrate placed
on the substrate support member 130 to deposit a layer on the
substrate surface. As the plasma is generated inductively and
externally from the showerhead 122, the amount of power used to
dissociate the process gas is not applied with respect to the
showerhead 122 and, more importantly, the substrate, which is atop
the support member 130. Thus, higher density plasma can thereby be
achieved between the showerhead 122 and substrate without directly
exposing the substrate to higher energy ion bombardment. This is an
important consideration for film deposition applications which are
sensitive to ion damage.
[0081] During an etching process, typically a non-polymerizing etch
gas such as chlorine, boron trichloride, hydrogen chloride, or the
like or other gas such as oxygen, any of the Group VIII noble gases
including argon and helium or the like is flowed through each
toroidal path 160-161 through gas inlets 111, 123, and the same
gases or any other etch gas such as carbon tetrafluoride, carbon
hexafluoride or like is flowed through the gas inlet 117 into the
showerhead assembly 122 and then through the showerhead gas
dispersion holes 121. The etch gas dissociates in the plasma to
produce an etching species between the showerhead 122 and a
substrate placed on the substrate support member 130. As the plasma
is generated inductively and externally from the showerhead 122,
the amount of power used to dissociate the process gas is not
applied with respect to the showerhead 122 and, more importantly,
the substrate, which is atop the support member 130. Thus, higher
density plasma can thereby be achieved between the showerhead 122
and substrate without directly exposing the substrate to higher
energy ion bombardment. This is an important consideration for film
etching applications which are sensitive to ion damage.
[0082] During a cleaning operation, a cleaning gas such as NF.sub.3
is flowed from the gas inlet 117 into the showerhead 122 and then
through the showerhead gas dispersion holes 121. The cleaning gas
or additional gas such as hydrogen, any of the Group VIII noble
gases including argon and helium, or like may also be flowed to
each toroidal plasma current path 160,161 through gas inlets 111,
123. The cleaning gas dissociates in the plasma to produce a
cleaning species within the processing region 120. As the power to
generate the cleaning species is applied external to the showerhead
122 and substrate support member 130, these parts are protected
from damage from ion bombardment from the cleaning species they
would otherwise be exposed to if the showerhead 122 and substrate
support member 130 were directly powered to generate the cleaning
plasma. Furthermore, if the cleaning gas such as NF3 is distributed
through the showerhead 122 and an inert gas is flowed through the
hollow conduits 124, 125 , the conduit surfaces and the surfaces of
the internal passageways of the showerhead 122 will not be exposed
to attack from the cleaning gas ions and radicals, and the cleaning
gas will not be needlessly "consumed" or neutralized by contact
with surfaces that do not have deposits on them.
[0083] In another embodiment, some processes may benefit from
adding more RF power to the process plasma directly through the
showerhead or by adding a RF bias to the substrate support member
130. Whether the process is deposition, etching or cleaning, it is
contemplated to apply additional power to the process plasma by
driving the showerhead 122 and/or the substrate support member 130
with separate RF power supplies and matching networks.
[0084] Although various embodiments which incorporate the teachings
of the invention have been shown and described in detail herein,
those skilled in the art can readily devise many other varied
embodiments within the scope of the invention. For example, only
one plasma-shaping apparatus of the first and second plasma-shaping
apparatus pair 150A-B, 151A-B and/or magnetic plasma shaping
apparatuses 180A-D may be needed to achieve adequate plasma
distribution. Furthermore, a plurality of conduits may be used to
define multiple toroidal plasma current paths each having at least
one plasma-shaping apparatus. Additionally, it is contemplated that
only one plasma current path may be used for processing where one
set of the plasma shaping apparatus pairs 150A-B and/or magnetic
plasma shaping apparatuses 180A-D are adapted to seal one plasma
current path. In another aspect, more than one plasma shaping
apparatus pairs 150A-B and/or magnetic plasma shaping apparatuses
180A-D may be placed in-line to create different opening patterns.
Further, the plasma shaping apparatuses 150A-B, 151A-B and/or
magnetic plasma shaping apparatuses 180A-D may be adjusted in-situ
to alter the plasma distribution in the process region by making
the entire plasma shaping apparatus or some elements of it
movable.
[0085] In another aspect, it is contemplated that the phase and
power of each RF source 115, 127 may be adjusted independently to
achieve the desired process plasma energy density distribution
within the processing region 120. By selecting various combinations
of power and phase of the showerhead RF source 119, the bias RF
source 146, and each inductive RF sources 115, 127, the density of
the plasma can be controlled over the larger rectangular substrates
to overcome non-uniform deposition or etching and/or increase
deposition or etch rates.
[0086] In another aspect, the showerhead RF source 128 may be used
to alter the plasma discharge within the processing region thereby
affecting deposition or etching. For example, the RF source 128 may
be increased in power to increase the power coupled to the plasma
current path adjacent the showerhead 122.
[0087] In still another aspect, the RF source 146 is used to alter
the deposition or etching process by adjusting the amount and/or
energy with which ion species are attracted to the substrate
surface. For example, the RF source 146 may be increased in power
to increase the ion species attraction to the substrate support
member 130.
[0088] While foregoing is directed to preferred embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
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